The invention relates generally to devices for placing bone anchors in bone, and in particular, to recessed bone anchor mounts used in connection with bone anchor drivers.
Urinary incontinence in women may be caused by urethral hypermobility, a condition in which the bladder neck and proximal urethra may rotate and descend in response to increases in intra-abdominal pressure. Hypermobility may be the result of aging, child delivery or conditions that weaken, stretch, or tear the muscles around the bladder, bladder neck and/or urethra. Urinary incontinence may also be caused by intrinsic sphincter deficiency (ISD), a condition in which the urethral sphincter does not coapt properly.
There are numerous approaches for treating urinary incontinence. In a bladder neck suspension procedure for treating hypermobility, sutures are placed around the muscle groups on either side of the urethra and are affixed to the pubic bone or other supporting structures to reposition and resuspend the proximal urethra. Also common are sling type operations, which may be performed to treat urethral hypermobility, intrinsic sphincter deficiency or both. In a sling type operation, a sling is placed under the urethra and bladder and is tensioned to elevate and stabilize the urethra, prevent excessive downward mobility, or compress the sphincter to treat intrinsic sphincter deficiency.
In these procedures, sutures are anchored to the supporting structures, such as the pubic bone, Cooper""s ligament, or the rectus fascia. Bone anchor placement devices, such as bone anchor drivers, may be used to place bone anchors at selected insertion sites in the pubic bone. Sutures may then be attached to the bone anchors.
To reduce postoperative patient discomfort, transvaginal surgical procedures for bone anchor placement are preferred over percutaneous procedures, which require an incision in the abdominal wall (and sometimes the vaginal wall) to introduce a bone anchor placement device, and can be highly invasive and traumatic to the patient. In a transvaginal procedure, vaginal incisions are made and bone anchors or similar attachment devices are secured to the posterior side pelvic wall through the vaginal incision. While being guided to the desired locations, the anchor placement device passes through multiple layers of tissue. During this process, an unprotected bone anchor can catch, tear or scrape tissue, snap a surgeon""s glove, or become dislodged.
It is desirable, therefore, to provide a protection mechanism for the bone anchor that prevents the sharp tip of the anchor from causing unintended tissue damage during passage of the anchor through tissue. At the same time, it is desirable that the head design for a bone anchor placement device be as compact as possible to minimize the necessary size of the vaginal incision through which the anchor placement device is inserted.
The present invention relates to manual bone anchor placement devices. The manual bone anchor placement devices disclosed herein are particularly useful in transvaginal methods of treating female urinary incontinence, although they can be used in other medical applications. The devices of the present invention are designed to permit rotational insertion of a bone anchor screw and to provide low cost alternatives to powered cannulated drills. The devices may be disposable or may be modular in nature, thereby allowing interchange of parts for reuse.
An advantage of the disclosed manual bone anchor placement devices is that they eliminate the need for a percutaneous incision to access an insertion area, although the devices can be used in a percutaneous procedure. A transvaginal approach to inserting a bone anchor screw into the pubic bone is far less invasive than a percutaneous procedure, thus a transvaginal procedure is far less traumatic for the patient.
An additional advantage of the disclosed manual bone anchor placement devices is that they seat a self-tapping bone anchor screw with a pre-attached suture. Since the bone anchor screw used with the disclosed devices is self-tapping and the suture is pre-attached, it is unnecessary for the physician to prebore a hole into the bone, remove the drill, introduce a seating device, seat the bone anchor screw, and then thread the suture. Single-step insertion of the bone anchor screw and suture not only reduces the total time required for the procedure, it also greatly reduces the possibility that the physician may lose access to the bored hole or seated bone anchor screw. Thus, the possible need to drill additional holes and/or seat additional bone anchor screws is reduced.
The manual bone anchor placement devices disclosed herein provide a mechanism to translate linear force exerted by a user on a lever into rotary force on a bone anchor screw. In one aspect of the invention, the manual bone anchor placement device includes a manually actuatable lever, a resilient element, a force translator, and a rotator. The force translator is coupled at its proximal end to the lever and at its distal end to the resilient element. The resilient element is coupled to the rotator. Linear force on the lever is transmitted through the force translator to the resilient element and from the resilient element to the rotator. The rotator rotates in response to this force. The device may further include a securing element coupled to the rotator that mates with a bone anchor screw and rotates when the rotator rotates, thereby applying a torque on the bone anchor screw and placing the bone anchor screw into bone.
In another aspect of the invention, the manual bone anchor placement device includes a manually actuatable lever, a force translator, a rack, and a rotator. The force translator includes a distal end and a proximal end, the proximal end receiving force from the lever, the distal end being coupled to the rack. The force translator transmits force to the rack, which moves linearly into an engaging position in response to this force. The rotator is positioned in close proximity to the rack for engagement with the rack when the rack moves into the engaging position. Engagement of the rotator by the rack causes the rotator to rotate. The device may further include a coupler coupled to the rotator that mates with a bone anchor screw and rotates when the rotator rotates, thereby placing the bone anchor screw into bone.
In another aspect of the invention, a manual bone anchor placement device is disclosed that includes a manually actuatable lever, a driver rod with threads, and a cup and washer positioned over the threads. The cup is coupled to the lever and moves axially along the driver rod upon actuation of the lever, engaging with the washer. When the cup and washer engage each other, linear force transmitted from the lever through the cup is translated to a rotary force on the driver rod, rotating the driver rod. The device may further include a coupling element for mating with a bone anchor screw and for rotating when the driver rod rotates to place the bone anchor screw into bone.
The present invention also relates to a self-tapping buttress-shaped bone anchor screw. The bone anchor screw of the present invention comprises a micropolished eyelet for receiving a suture. The eyelet may be circular, ellipsoidal, or teardrop shaped. The bone anchor screw described herein is designed to require less torque to seat and to minimize load on a pre-attached suture in comparison with known bone anchor screws.
Kits are also disclosed comprising any of: a molded flexible sleeve for enclosing a suture, a retaining clip for preventing the suture from slipping out of the sleeve, a buttress-shaped bone anchor screw comprising a micropolished eyelet for receiving a suture, and a suture which may, or may not, be pre-attached to the bone anchor screw. A collapsible, protective cover for a bone anchor screw is also disclosed.
In yet another aspect of the invention, the manual bone anchor placement device includes a head assembly, a recessed anchor mount movably disposed within the head assembly, and an actuation mechanism coupled to the recessed anchor mount. In various embodiments, the actuation mechanism can be a push wire or a pull wire, and the mechanism actuates the recessed anchor mount between a recessed position and an advanced position. The anchor mount can include an outer surface having at least one flat surface and the head assembly can have a core comprising a mating shape. Further, the manual bone anchor placement device can include a bone anchor releasably engaged to the anchor mount. In addition, the anchor mount can include a groove for accommodating a suture attached to the bone anchor.
In still another aspect of the invention, the manual bone anchor placement device includes a handle, a shaft extending in a distal direction from the handle, a head assembly disposed at a distal end of the shaft, a recessed anchor mount movably disposed within the head assembly, and an actuation mechanism coupled to the recessed anchor mount. In various embodiments, the actuation mechanism can be a push wire or a pull wire, and the mechanism actuates the recessed anchor mount between a recessed position and an advanced position. Further, the actuation mechanism can be situated within a channel disposed on the handle, an actuator disposed on the handle can operate the actuation mechanism, and the actuation mechanism may be manufactured of spring steel or nitinol. The anchor mount can include an outer surface having at least one flat surface and the head assembly can have a core comprising a mating shape. Further, the manual bone anchor placement device can include a bone anchor releasably engaged to the anchor mount. In addition, the anchor mount can include a groove for accommodating a suture attached to the bone anchor. Still further, the manual bone anchor placement device can include a stop disposed within the head assembly, for example within the core. Alternatively, the stop can be located on the actuation mechanism.
These and other objects, along with advantages and features of the present invention herein disclosed, will become apparent through reference to the following description of embodiments of the invention, the accompanying drawings, and the claims. Furthermore, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and permutations.